The CMC of mixed gangliosides was measured by boundary sedimentation on a sucrose gradient. The binding constants, inactivation rates and oxidation rates of various goitrogens by lactoperoxidase have been evaluated in the absence and presence of iodide. The molecular properties of serum cold-insoluble globulin have been compared to those of the cell surface protein isolated from chicken fibroblasts. It has been shown that a conformational change occurs when T4 is bound to prealbumin.